A block through which hosts provide information about their transport state.
SDKs
- iOS 10.0+
- macOS 10.12+
- Mac Catalyst 13.0+
- tvOS 10.0+
Framework
- Audio
Toolbox
Declaration
typealias AUHostTransportStateBlock = (Unsafe Mutable Pointer<AUHost Transport State Flags>?, Unsafe Mutable Pointer<Double>?, Unsafe Mutable Pointer<Double>?, Unsafe Mutable Pointer<Double>?) -> Bool
Discussion
If the host app provides this block to an audio unit, via the transport
property, then the block may be called at the beginning of each render cycle to obtain information about the current transport state. Any of the provided parameters may be null to indicate that the audio unit is not interested in that particular piece of information.
This block returns true
if the transport state was able to be retrieved from the host; it returns false
otherwise.
The block takes the following parameters:
- transportStateFlags
The current state of the audio transport.
- currentSamplePosition
The current position in the host’s timeline, in samples at the audio unit’s output sample rate.
- cycleStartBeatPosition
If cycling, the starting beat position of the cycle.
- cycleEndBeatPosition
If cycling, the ending beat position of the cycle.